We have studied the efficacy of anti-reflux procedures in preventing pyelonephritis, hydronephrosis and renal damage in dogs. Our data in 18 dogs indicates that submucosal tunnel procedure is an effective anti-reflux procedure in reducing the incidence of ascending renal infection and hydronephrosis. It appears that anti-reflux submucosal tunnel procedure is superior to the conventional refluxing urinary diversion. We have started to apply anti-reflux sigmoid conduit urinary diversion to patients with pelvic malignancies needing urinary diversion.